View that displays my ManyToManyField('self'...) relations in a <ul> with levels

[M. GW]

Hi,

I am now trying, for days, to get a tree like view from my assembly model into my template. I think I have read everything what I have found on StackOverflow and other sites. Somehow I am not able to get it working. I am trying to not use any 3rd party extensions => I'm happy to be proven wrong. But first let me explain my topic:

This are my models:

class Assembly(models.Model):

    reference = models.OneToOneField('products.Reference', on_delete=models.RESTRICT, verbose_name=_('reference'))

    subassembly = models.ManyToManyField(SubAssembly, blank=True, verbose_name=_('subassembly'))

    component = models.ManyToManyField(Component, blank=True, verbose_name=_('component'))

class SubAssembly(models.Model):

    reference = models.CharField(max_length=40, default=None)

    subassembly_class = models.ForeignKey(SubAssemblyClass, on_delete=models.CASCADE)

    nested_subassembly = models.ManyToManyField(

        'self', symmetrical=False, blank=True)

class SubAssemblyClass(models.Model):

    name = models.CharField(max_length=255)

class Component(models.Model):

    reference = models.CharField(max_length=40, unique=True)

    component_class = models.ForeignKey(ComponentClass, on_delete=models.CASCADE)

    nested_component = models.ManyToManyField('self', blank=True')

class ComponentClass(models.Model):

    name = models.CharField(max_length=255, unique=True)

For my view I am using the class based one. I am generally using CBV's

class AssemblyDetailView(LoginRequiredMixin, DetailView):

    model = Assembly

    template_name = "engineering/assembly/assembly_detail.html"

Now I want in my template all children of subassembly and component from one assembly like this:

assembly1

* subassembly1

* subassembly5

* component5

* component7

* component8

* subassembly6

* component7

* component8

* component1

* component2

* subassembly2

* component3

* subassembly3

* subassembly6

* component1

* component2

* component1

* component3

The depth can be infinity but for now there will be only 3-5 levels. I don’t care if it will be Depth-first-search or Breadth-first-search. I read a lot about recursive common table expressions and raw queries. I haven’t found a way to code the logic with my complicated ManyToMany fields.

I hope there is someone out there who can help me out. Maybe I have build up the models in a wrong way and that’s causing the problems why I am not able to solve it or or something else.

Thank you for your help!

[David Crandell]

I would create two dictionaries, one for subassembly and one for component.

then in your view, loop through the first group, pulling your data from a master dataset:

assem = Assembly.objects.all()

sa = assem.subassembly.all()

comp = assem.component.all()

send 'sa' and 'comp' to your template as context variables

Then in your template, loop through 'sa' with an inner loop of 'comp' and you should be able to manipulate the output like what you're seeking.

[Nader Elsisi]

I noticed that subassembly 6 has different components in use. Is that what you want.

--
You received this message because you are subscribed to the Google Groups "Django users" group.
To unsubscribe from this group and stop receiving emails from it, send an email to django-users...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/django-users/95ef56a4-6fc5-4cdd-9d4a-9090e364a308n%40googlegroups.com.

[Marko]

Hey,

thank you. I tried your approach and is looks very promising but I am getting an error. Here is my view:

class AssemblyDetailView(LoginRequiredMixin, DetailView):

    model = Assembly

    template_name = "engineering/assembly/assembly_detail.html"

    assem = Assembly.objects.all()

    sa = assem.subassembly.all()

    comp = assem.component.all()

    def get_context_data(self, **kwargs):

        context = super().get_context_data(**kwargs)

        context['sa'] = self.sa

        context['comp'] = self.comp

        return context

Console tells me:

AttributeError: 'QuerySet' object has no attribute 'subassembly'

print(assem) gives me the right QuerySet:

<QuerySet [<Assembly: assembly1>]>

It's been a long day but I had to try your suggestion today! Maybe I'm just tired and do not recognise the current problem...

[Marko]

Yes, my example is not right. Both should be the same!